What does a Pressure Relief Valve do when the pressure exceeds a set point?

A Pressure Relief Valve (PRV) is designed to protect systems by managing pressure levels. When the pressure exceeds a predetermined set point, the PRV automatically opens to release excess pressure. This action allows fluid or gas within the system to escape, helping to prevent potential overpressure situations that could lead to equipment failure or hazards. By releasing the pressure, the valve returns the system back to an acceptable pressure level, ensuring safe operation and preventing damage to components.

The other options describe actions that do not align with the fundamental function of a PRV. Increasing the flow rate does not address overpressure; closing the valve would only compound the problem by not allowing pressure relief, and alerting control systems is a monitoring function rather than an action to relieve pressure. Therefore, the correct description of a PRV's function is that it releases pressure to maintain safe operating conditions.